Table 4 Baseline characteristics of 86,925 WHI study participants by preterm birth status
From: Associations between birthweight and preterm birth and the ages at menarche and menopause
| Â | Preterm birth N = 2,042 | Full term N = 84,883 | Pa | |
|---|---|---|---|---|
Age at baseline (years) | 62.0 (7.3) | 63.5 (7.4) | < 0.0001 | |
Race | Â | Â | Â | |
| Â | Asian/Pacific Islander | 44 (2.2) | 2,327 (2.8) | 0.43 |
| Â | Black | 162 (8.1) | 6,621 (8.0) | |
| Â | White | 1,770 (88.4) | 72,954 (87.9) | |
| Â | Other/Unknown | 26 (1.3) | 1,135 (1.4) | |
Ethnicity | Â | Â | Â | |
| Â | Hispanic/Latinx | 83 (4.1) | 3,588 (4.3) | 0.71 |
| Â | Not Hispanic/Latinx | 1,941 (95.9) | 80,472 (95.7) | |
Region | Â | Â | Â | |
| Â | Northeast | 425 (20.8) | 19,296 (22.7) | 0.23 |
| Â | South | 548 (26.8) | 22,004 (25.9) | |
| Â | Midwest | 462 (22.6) | 18,788 (22.1) | |
| Â | West | 607 (29.7) | 24,795 (29.2) | |
Education | Â | Â | Â | |
|  | ≤ High school diploma/GED | 363 (17.9) | 17,715 (21.0) | 0.002 |
| Â | School after high school | 744 (36.7) | 30,679 (36.4) | |
| Â | College degree or higher | 918 (45.3) | 35,820 (42.5) | |
Normalized Socioeconomic Status (NSES) | 75.8 (8.2) | 76.0 (8.6) | 0.26 | |
BMI at baseline (kg/m2) | 27.7 (6.1) | 27.2 (5.9) | 0.0001 | |
Smoking status | Â | Â | Â | |
| Â | Never | 1,039 (51.6) | 42,422 (50.6) | 0.09 |
| Â | Past | 828 (41.2) | 36,110 (43.1) | |
| Â | Current | 145 (7.2) | 5,246 (6.3) | |
Alcohol Use | Â | Â | Â | |
| Â | Non-drinker | 218 (10.7) | 9,316 (11.1) | 0.31 |
| Â | Past drinker | 406 (20.0) | 15,709 (18.6) | |
| Â | Current drinker | 1,410 (69.3) | 59,310 (70.3) | |
Participant breast fed | Â | Â | Â | |
| Â | Yes | 882 (53.6) | 50,863 (74.4) | < 0.0001 |
| Â | No | 765 (46.5) | 17,513 (25.6) | |
Birthweight | Â | Â | Â | |
| Â | < 6 lbs. | 1,687 (84.6) | 6,359 (8.4) | < 0.001 |
|  | 6 lbs. – 7 lbs. 15 oz. | 277 (13.9) | 51,728 (67.9) | |
|  | 8 lbs. – 9 lbs. 15 oz. | 29 (1.5) | 15,414 (20.2) | |
|  | ≥ 10 lbs. | < 20 (<1.0) | 2,638 (3.5) | |
Age at menarche (years) | Â | Â | Â | |
|  | ≤ 11 | 502 (24.7) | 18,646 (22.1) | 0.03 |
| Â | 12 | 527 (25.9) | 22,112 (26.2) | |
| Â | 13 | 551 (27.1) | 24,571 (29.1) | |
| Â | 14 | 452 (22.2) | 19,214 (22.7) | |
Age at first regular period (years) | Â | Â | Â | |
|  | ≤ 11 | 253 (15.3) | 9,903 (14.0) | 0.46 |
| Â | 12 | 343 (20.8) | 14,742 (20.8) | |
| Â | 13 | 424 (25.7) | 18,418 (26.0) | |
| Â | 14 | 633 (38.3) | 27,900 (39.3) | |
Age at last regular period (years) | 46.8 (6.8) | 47.5 (6.6) | < 0.0001 | |
Age at last vaginal bleeding (years) | 47.7 (7.6) | 48.4 (7.3) | < 0.0001 | |
Were periods regular | Â | Â | Â | |
| Â | Yes | 1,599 (78.9) | 69,651 (82.5) | < 0.0001 |
| Â | No | 427 (21.1) | 14,730 (17.5) | |
Ever had a hysterectomy | Â | Â | Â | |
| Â | Yes | 889 (43.6) | 35,297 (41.6) | 0.08 |
| Â | No | 1,151 (56.4) | 49,512 (58.4) | |
Ever had an oophorectomy | Â | Â | Â | |
| Â | Yes | 644 (31.9) | 24,483 (29.2) | 0.009 |
| Â | No | 1,373 (68.1) | 59,269 (70.8) | |
Age at natural menopause (years) | 48.4 (6.3) | 49.1 (5.9) | < 0.0001 | |
Ever had premenopausal hot flashes | Â | Â | Â | |
| Â | Yes | 1,682 (82.4) | 70,802 (83.5) | 0.18 |
| Â | No | 360 (17.6) | 14,013 (16.5) | |
Ever had postmenopausal hot flashes | Â | Â | Â | |
| Â | Yes | 687 (51.4) | 28,807 (49.0) | 0.09 |
| Â | No | 651 (48.7) | 29,296 (51.1) | |
Reproductive window (years) | 35.9 (6.3) | 36.5 (6.0) | < 0.0001 | |